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of the Equatorial Instrument. 
one side of which is seen at U, and its exterior extremity 
near V, with its sliding plate and screws for adjustment. 
Close behind the graduated circle, and at right angles to this 
axis, passing through it, lies the telescope T S, feet long. 
This circle is likewise furnished with two microscopes, and 
micrometers, as in the equatorial circle, one of which is seen 
at full length at Y and Z, the eye tube being at Y, and the 
object glass, with the perforated speculum to throw light, at 
Z ; the other microscope, on the opposite side of the circle, 
is not so discernible in the drawing, being completely fore- 
shortened at Z near T, the eye of the draftsman having been 
exactly in the axis of the tube of the microscope, a, a, a, u, u, 
is an hexagonal lozenge, composed of six brass rulers, firmly 
fixed to the columns AB and EF, and supporting the lower 
end of the microscopes, as the pieces (3/3, (3/3, in like manner, 
sustain the upper end. By these means the wire in the field 
of the microscopes becomes a fixed immoveable index, and, 
after proper adjustment, an exact diameter of the circle, whilst 
the telescope, together with the circle, turns round the coni- 
cal axis before mentioned. At P is a spirit level, passing 
through the centre plate of the conical axis at right angles to 
the telescope, supported by a cock at each end, one of which 
appears at k ; this cock is fixed to the cone U, and, by means 
of a small toothed wheel and pinion, the level is made to re- 
volve round its own axis, so that the same side of the level 
may readily be brought uppermost, whatever position the 
circle be put into ; it is also furnished with all necessary ad- 
justing screws. It will readily be seen that a telescope, thus 
fitted up, will have all the properties of a transit instrument, 
